RC tuning of touch electrode connections on a touch sensor panel

Abstract

A touch sensor panel comprising a first touch node electrode of a plurality of touch node electrodes, the first touch node electrode coupled to a first sense connection comprising a first set of traces, the first sense connection configured to have a first resistance per unit length that varies along a length of the first sense connection, and a second touch node electrode of the plurality of touch node electrodes, the second touch node electrode coupled to a second sense connection comprising a second set of traces, the second sense connection configured to have a second resistance per unit length that varies along a length of the second sense connection differently than the first resistance per unit length varies along the length of the first sense connection. An effective resistance of the first sense connection and the second sense connection are equal.

The invention claimed is: 
     
       1. A touch sensor panel comprising:
 a first touch node electrode of a plurality of touch node electrodes, the first touch node electrode coupled to a first sense connection comprising a first set of traces, the first sense connection configured to have a first resistance per unit length that varies along a length of the first sense connection; and 
 a second touch node electrode of the plurality of touch node electrodes, the second touch node electrode coupled to a second sense connection comprising a second set of traces, the second sense connection configured to have a second resistance per unit length that varies along a length of the second sense connection differently than the first resistance per unit length varies along the length of the first sense connection, 
 wherein a resistance of the first sense connection and the second sense connection are equal. 
 
     
     
       2. The touch sensor panel of  claim 1 , wherein the first touch node electrode and the second touch node electrode are both in either a row or a column of touch node electrodes on the touch sensor panel. 
     
     
       3. The touch sensor panel of  claim 1 , wherein the first sense connection comprises a first number of traces, and the second sense connection comprises a second number of traces, equal to the first number of traces. 
     
     
       4. The touch sensor panel of  claim 1 , wherein:
 the first sense connection comprises a first portion and a second portion configured to couple the first touch node electrode to sense circuitry, the first portion of the first sense connection comprising a first number of traces of the first set of traces coupled together, in parallel, and the second portion of the first sense connection comprising a second number of traces, different from the first number of traces, of the first set of traces coupled together, in parallel, and 
 the second sense connection comprises a first portion and a second portion configured to couple the second touch node electrode to the sense circuitry, the first portion of the second sense connection comprising a first number of traces of the second set of traces coupled together, in parallel, and the second portion of the second sense connection comprising a second number of traces, different from the first number of traces, of the second set of traces coupled together, in parallel. 
 
     
     
       5. The touch sensor panel of  claim 4 , wherein a length of the first portion of the first sense connection and a length of the first portion of the second sense connection are different. 
     
     
       6. The touch sensor panel of  claim 4 , wherein a length of the second portion of the first sense connection and a length of the second portion of the second sense connection are different. 
     
     
       7. The touch sensor panel of  claim 1 , wherein a capacitance of the first sense connection is equal to a capacitance of the second sense connection. 
     
     
       8. The touch sensor panel of  claim 1 , wherein a first respective portion of a first trace of the first set of traces is coupled to the second sense connection. 
     
     
       9. The touch sensor panel of  claim 8 , wherein:
 the first trace includes a first portion and a second portion, the second portion of the first trace comprising the first respective portion of the first trace, and the first portion of the first trace decoupled from the second portion of the first trace, 
 the first portion of the first trace is configured to couple the first touch node electrode to sense circuitry, and 
 the second portion of the first trace is configured to couple the second touch node electrode to the sense circuitry. 
 
     
     
       10. The touch sensor panel of  claim 9 , wherein the second portion of the first trace is coupled, in parallel, to at least a portion of the second set of traces in the second sense connection. 
     
     
       11. The touch sensor panel of  claim 9 , further comprising:
 a third touch node electrode of the plurality of touch node electrodes, the third touch node electrode coupled to a third sense connection comprising a third set of traces, 
 wherein a first respective portion of a second trace of the second set of traces, and a second respective portion of the first trace of the first set of traces are coupled to the third sense connection. 
 
     
     
       12. The touch sensor panel of  claim 11 , wherein:
 the first trace further includes a third portion, the third portion of the first trace comprising the second respective portion of the first trace, and the third portion of the first trace decoupled from the first and second portions of the first trace, 
 the second trace includes a first portion and a second portion, the second portion of the second trace comprising the first respective portion of the second trace, and the first portion of the second trace decoupled from the second portion of the second trace, 
 the first portion of the second trace is configured to couple the second touch node electrode to the sense circuitry, and 
 the second portion of the second trace and the third portion of the first trace are configured to couple the third touch node electrode to the sense circuitry. 
 
     
     
       13. The touch sensor panel of  claim 12 , wherein the second portion of the second trace and the third portion of the first trace are coupled, in parallel, to at least a portion of the third set of traces in the third sense connection. 
     
     
       14. The touch sensor panel of  claim 1 , further comprising:
 a third touch node electrode and a fourth touch node electrode in a column of touch node electrodes on the touch sensor panel, the column of touch node electrodes including the first touch node electrode and the second touch node electrode, the third touch node electrode coupled to a third sense connection comprising a third set of traces, and the fourth touch node electrode coupled to a fourth sense connection comprising a fourth set of traces, 
 wherein:
 the first touch node electrode is separated from the second touch node electrode by a first number of touch node electrodes, 
 the third touch node electrode is separated from the fourth touch node electrode by the first number of touch node electrodes, 
 a number of traces in the first set of traces equals a number of traces in the third set of traces, and 
 a number of traces in the second set of traces equals a number of traces in the fourth set of traces. 
 
 
     
     
       15. The touch sensor panel of  claim 14 , wherein the first touch node electrode is adjacent the third touch node electrode on the touch sensor panel, and the second touch node electrode is adjacent the fourth touch node electrode on the touch sensor panel. 
     
     
       16. The touch sensor panel of  claim 14 , wherein the first sense connection and the second sense connection are disposed in a first region of the touch sensor panel, and the third sense connection and the fourth sense connection are disposed in a second region of the touch sensor panel, other than the first region, adjacent the first region. 
     
     
       17. A method of fabricating a touch sensor panel, the method comprising:
 forming a first touch node electrode of a plurality of touch node electrodes, the first touch node electrode coupled to a first sense connection comprising a first set of traces, the first sense connection configured to have a first resistance per unit length that varies along a length of the first sense connection; and 
 forming a second touch node electrode of the plurality of touch node electrodes, the second touch node electrode coupled to a second sense connection comprising a second set of traces, the second sense connection configured to have a second resistance per unit length that varies along a length of the second sense connection differently than the first resistance per unit length varies along the length of the first sense connection, 
 wherein a resistance of the first sense connection and the second sense connection are equal.